Revert "Add number ordering to SkFilterQuality"

This reverts commit af68258c2eee593160996893c2c5e3c110e03024.

Reason for revert: SkFilterQuality is not a scoped enum, so this defines `kMaxValue` without any scoping to Skia by naming convention or namespace, breaking compatibility with other systems that want to use that.  (E.g. Android)

Original change's description:
> Add number ordering to SkFilterQuality
>
> As explained in the bug, I would like to add a histogram to study how
> users use the image smoothing quality in Chrome. In order to do that,
> we need to ensure that the enums are not reordered or changed, so I
> added kNone_SkFilterQuality = 0, etc. I also added kMaxValue for
> histogram to work.
>
> Bug: 1176091
> Change-Id: I3af3213f699016a525caad5b0b51e0cc7aab2c52
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/368157
> Commit-Queue: Mike Reed <reed@google.com>
> Auto-Submit: Yi Xu <yiyix@chromium.org>
> Reviewed-by: Mike Reed <reed@google.com>

TBR=reed@google.com,yiyix@chromium.org

Change-Id: Iec24ba3864af69e34f2721a72de1c0a271d328f6
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1176091
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/371936
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
diff --git a/include/core/SkFilterQuality.h b/include/core/SkFilterQuality.h
index 04d3b6c..1f89517 100644
--- a/include/core/SkFilterQuality.h
+++ b/include/core/SkFilterQuality.h
@@ -15,13 +15,12 @@
  *  e.g. images
  */
 enum SkFilterQuality {
-    kNone_SkFilterQuality = 0,      //!< fastest but lowest quality, typically nearest-neighbor
-    kLow_SkFilterQuality = 1,       //!< typically bilerp
-    kMedium_SkFilterQuality = 2,    //!< typically bilerp + mipmaps for down-scaling
-    kHigh_SkFilterQuality = 3,      //!< slowest but highest quality, typically bicubic or better
+    kNone_SkFilterQuality,      //!< fastest but lowest quality, typically nearest-neighbor
+    kLow_SkFilterQuality,       //!< typically bilerp
+    kMedium_SkFilterQuality,    //!< typically bilerp + mipmaps for down-scaling
+    kHigh_SkFilterQuality,      //!< slowest but highest quality, typically bicubic or better
 
     kLast_SkFilterQuality = kHigh_SkFilterQuality,
-    kMaxValue = kLast_SkFilterQuality,
 };
 
 #endif